Network attached storage (“NAS”) is a common way for organizations to store and manage data separately from the client computers that are creating and accessing the data. NAS includes devices, computers, filers and other types of file servers connected over a network, as shown in FIG. 1A. Client computers 111 will have access to the network and will thereby be able to interact with these file servers 121. Since more than one computer is likely to access a file server, each file server is known as a “shared resource,” and each set of files and directories made available to client computers 111 is known as a “network share” or “share.” A client computer accesses a file stored on a file server by referring to a mapping index that provides a host name or IP address, share name or export name, or other location information for the share containing the requested file. For example, client computer 101 of FIG. 1A will need to know the mapping information of a share on file server 131 in order to access to access any files stored in that share.
It is not uncommon for an organization to manage a number of different file servers. Over time, these file servers may be replaced or joined by additional file servers. Similarly, file servers may be taken off the network for repair, retirement or other reasons. Also, shares may be created, deleted, merged, and/or split. These changes to the network and file servers significantly affect the mapping indices used by client computers to access respective file servers. Every time the NAS configurations change, the client computers need to update their mapping indices in order to maintain proper access to associated shares. Although network information service (NIS) servers may provide updated mapping information for some NAS clients, they may not be usable by all clients and may also be difficult to maintain consistently. While distributed file system (DFS) servers do automate access for some NAS clients, they are unusable by other clients. What is therefore needed is a more efficient and universal way to manage mapping information for file servers regardless of their locations on the network.
One will appreciate that file servers may be accessed over the network by using different protocols, the two most common being CIFS and NFS. Data stored for CIFS access on a file server will be organized and accessed differently than data stored for NFS access. Additionally, the mapping information for the different protocols is generated, stored, maintained and accessed differently depending upon the protocol used. As a result, client computers accessing shares on a CIFS file server will not be able to use the same techniques to access shares on a NFS file server. As such, some client computers may be configured to only access shares on a CIFS file server, or configured to only access shares on a NFS file server. As shown in FIG. 1A, some of the client computers may be configured to only use NFS, and so may only be able to access NFS file servers. Similarly, some client computers may be configured to only use CIFS, and so may only be able to access CIFS file servers. One will appreciate that there are some file servers and even some client computers that can support both CIFS and NFS protocols, i.e., multi-protocol file servers and client computers. However, access between multi-protocol client computers and file servers still requires different mapping information depending upon the protocol used, and multi-protocol access is not necessarily seamless.
One will appreciate that mapping information may comprise more than simply direct access to a host or IP address. Some mapping information may include what are known in the art as “referrals.” For example, some NAS protocols support referrals (e.g. DFS) whereby a client can request that a server provide access to a named file, and the server can refer that client to another server, which actually contains the named file.
Other NAS protocols may not support referrals. Clients using such protocols often retrieve NAS mapping information from another server such as a NIS server. For example, in FIG. 1A, client 101 may be a client that only uses non-referral-based NAS protocols and uses zero or more NAS mapping NIS servers 141. Client 105 may be a client that only uses referral-based NAS protocols and uses zero or more NAS referral servers 143. Client 103 may be a client that uses both referral- and non-referral-based NAS protocols and use zero or more NAS referral servers 143 and NAS mapping NIS servers 141. Servers 131 and 135 may be servers that implement a single NAS protocol. Server 133 may be a server that implements multiple NAS protocols. The addition of various mapping NIS servers 141 and/or referral servers 143, as well as the presence or absence of file servers having different protocols complicates access between client computers 111 and file servers 121.
What is therefore needed is a way to provide access from client computer to file server, regardless of the protocol used and the type of file server on the network.